I have a 60" hybrid bow Bob Lee I cannot get even close to being quite.I have played with 4 or 5 strings
numorus brace hgt.I have a leather rest and recurve limbs @ 58" with a Mountain Muffler is dead quite.The best I can do with longbow limbs is beaver two fur silencer.I do not think the string is hitting the limbs.Any thoughs much appreated.It is a Bob Lee and I had another one just like it and was very quite but one limb blew cracked riser a few years ago finally found a replacement.Thanks

Have you checked to see if the limbs are tight ?
Also you might try a heavier arrow .

Also check the tiller.  Will be noisy if it's out of tiller.

I will try a heavy arrow. Never thought about tiller bought limbs used and will try tiller.Thanks keep ideas coming.